Hi Steve,
Many thanks for looking into this, especially as you don’t have to. When the SonoreUPnP Bridge is stopped, the BBC stations in iRadio play just fine, so your product is working in this area without issue 
I also believe that the UPnP bridge is basically bashing the UPnP interface in the renderer and making it play the provided stream, given that the renderer is not requesting it from a UPnP server, as in normal DNLA type operation.
However, it does work and the Roon integration makes for a good experience, and the SQ is equivalent to the stream coming from a UPnP server such as Asset or a Naim Core.
In terms of this product, there are two manifestations:
- A software ‘App’ available within the SonicOrbiterOS that runs on the Sonore UltraRendu and SGC SonicTransporter platforms
- A dedicated appliance offered by SGC (Small Green Computer) that just runs the SonoreUPnP Bridge under SonicOrbiterOS. I believe loading of other components is disabled in the GUI, to provide the appliance level operation.
It is this product which is listed as having the supply chain parts issue, as it was RPi based, but I think it has basically been withdrawn. I would imagine that SGC would prefer to sell a complete SonicTransporter product, which is a Intel CPU based server for the Roon Core, storage for a Music Library and can run the SonoreUPnP Bridge alongside.
I run the SonoreUPnP Bridge on a UltraRendu. Sonore loosely supports this through the forum and the group here Including SonoreUPnP Bridge with SonicOrbiter OS 2.9 - Page 3 - Sonore (Sponsored) - Audiophile Style
But as you can see there is little activity. The latest release on SonicOrbiterOS 2.9 was a late addition prompted by a few users, and I would say will be left ‘as is’ since it is deemed operation and stable on this latest version of the SonicOrbiterOS. There doesn’t seem to be any move to a later version, as they have had issues with the latest Linux 6.2.x & 6.6.x kernels (current version is 6.0.x based)
The underlying component for the UPnP Bridge was actually developed as the ‘LMS2UPNP’ plugin to LMS (or whatever it is called now), as an OpenSource community developed element.
The Github page is at GitHub - philippe44/LMS-uPnP: Integrate UPnP players with LogitechMediaServer
Now I do have a version of this, deployed to my RPi2, as also part of my fallback measures, alongside the Asset UPnP server.
Let me stop the SonoreUPnP Bridge, enable this instance and see if this interferes with the BBC stations in iRadio in the same way, to see if the problem exists in the core library of LMS2UPNP or Sonore’s version.
Also, if you provide a link to the UPNP Device Spy / Validator tools you are using, so I can see what errors are being thrown on the network, to see if this sheds any light on the issue.